Before the idea of freedom for people to chart their own course, ALL were slaves. The King or Queen of England allowed some to own land, the rest were sharecroppers. Being a slave in Biblical times, was akin to being an employee.
The yeomen/socmen/freeholders were a consequence of the drastic depopulation during and after the Black Death. Their labor was at a premium and they seized the advantage.
They demanded emancipation from serfdom and the right to own land for themselves and their descendants. And they got it.
And that really was the foundation of England as a constitutional monarchy, the barons never could have put the screws to John without the support of the independent landowning class. Also, England's victories in Europe were a consequence of those freeholding soldiers of the independent companies. Great books, read all about it:
Conan Doyle wrote Sherlock Holmes to make money, but he wrote these for love. And his history is well researched.